1. Field
The present invention generally relates towards reducing communication latency in communication systems. More particularly, the present invention relates to an optimistic access procedure for communication with a dormant target handset.
2. Background
Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5G and 2.75G networks) and a third-generation (3G) high speed data/Internet-capable wireless service. There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Examples of known cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), the Global System for Mobile access (GSM) variation of TDMA, and newer hybrid digital communication systems using both TDMA and CDMA technologies.
The method for providing CDMA mobile communications was standardized in the United States by the Telecommunications Industry Association/Electronic Industries Association in TIA/EIA/IS-95-A entitled “Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,” referred to herein as IS-95. Combined AMPS & CDMA systems are described in TIA/EIA Standard IS-98. Other communications systems are described in the IMT-2000/UM, or International Mobile Telecommunications System 2000/Universal Mobile Telecommunications System, standards covering what are referred to as wideband CDMA (WCDMA), CDMA2000 (such as CDMA2000 1xRTT, “1x”, and 1xEV-DO standards, “1XEV”, for example) or TD-SCDMA.
In wireless communication systems, mobile stations or access terminals receive signals from fixed position base stations (also referred to as cell sites or cells) that support communication links or service within particular geographic regions adjacent to or surrounding the base stations. In order to aid in providing coverage, each cell is often sub-divided into multiple sectors, each corresponding to a smaller service area or geographic region. An array or series of base stations placed adjacent to each other form a communication system capable of servicing a number of system users, over a larger region.
Typically, each mobile station monitors a control channel that can be used to exchange messages between the mobile station and the base station. The control channel is used to transmit system/overhead messages, whereas traffic channels are typically used for substantive communication (e.g., voice and data) to and from the mobile station.
For example, the control channel can be used to establish traffic channels, control power levels, and the like and is known in the art. Generally, there are two types of power control for the reverse link, open-loop and closed-loop power control. The open-loop power control typically occurs prior to the mobile terminal establishing contact with a base station. The closed-loop control occurs after the mobile and the base station are in communication and the base station can measure the received power levels and feedback power level adjustments to the mobile terminal.
In the open loop condition, the reverse link power for an initial communication signal (e.g., access probe) from the mobile terminal to the base station can be determined by monitoring specialized signals from a base station or access point. For example, in CDMA systems, a pilot signal can be used to estimate the channel condition and then determine a power estimate for transmitting back to the base station. The accuracy of the channel conditions and power estimation can greatly impact performance of the system, particularly in terms of latency of the system. For example, 1x and 1xEV systems will transmit an access probe at a first power level based on a power control algorithm. If the first access attempt does not succeed, then the probe is resent at increasingly higher power levels, until it is successful or the power level maximum is reached.
In addition to the message loss due to power related issues (e.g., channel fading, time-varying RoT, etc.), Access Channel losses can also occur because of access probe collisions may be the case in geographically dense group calls. Losses that are caused due to the fading of the wireless channel can be minimized by increasing the transmit power of access probes. Losses due to probe collisions over the Access channel can be mitigated by ensuring that probe transmissions that are synchronized with respect to each other do not transmit their probes at the same time.
Additionally, advances in technology have resulted in smaller and more powerful personal computing devices. For example, there currently exist a variety of portable personal computing devices, including wireless computing devices, such as portable wireless telephones, laptops, personal digital assistants (PDAs) and paging devices that are each small, lightweight, and can be easily carried by users. A wireless device is any device that can communicate with other devices without being physically attached to them. Most wireless devices communicate with each other through radio frequencies.
More specifically, the portable wireless telephones, for example, further include cellular telephones that communicate voice and data packets over wireless networks. Further, many such cellular telephones are being manufactured with relatively large increases in computing capabilities, and as such, are becoming tantamount to small personal computers and hand-held PDAs.
However, these smaller and more powerful personal computing devices are typically severely resource constrained. For example, the screen size, amount of available memory and file system space, amount of input and output capabilities and processing capability may each be limited by the small size of the device. Due to severe resource constraints, it is often typically desirable, for example, to maintain a limited size and quantity of software applications and other information residing on such remote personal computing devices (client devices).
Some of the personal computing devices utilize an application programming interface (API) or application programming interfaces (APIs), sometimes referred to as runtime environments and software platforms, that are installed onto their local computer platform and which are used, for example, to simplify operations of such devices, such as by providing generalized calls for device specific resources. An API is a set of routines used by an application program to direct the performance of procedures used by the computer's operating system.
Further, some APIs are also known to provide software developers the ability to create software applications that are fully executable on such devices. In addition, some of such APIs are known to be operationally located between the computing device system software and the software applications such that the computing device system software and the software applications such that the computing device computing functionality is made available to the software application without requiring the software developer to have the specific computing device system source code. Further, some APIs are known to provide mechanisms for secure communications between such personal devices (i.e., clients) and remote devices (i.e., servers) using secure, cryptographic information.
Examples of such APIs, some of which are discussed in more detail below, include versions of the Binary Runtime Environment for Wireless® (BREW®) developed by QUALCOMM, Inc., of San Diego, Calif. BREW® can operate with a computing device's (e.g., a wireless cellular phone) operating system, and can, among other features, provide interfaces to hardware features particularly found on personal computing devices. BREW® can also provide these interfaces on such personal computing devices at a relatively low cost with respect to demands on device resources and with respect to the price paid by consumers for devices containing the BREW® API. Additional features of BREW® include its end-to-end software distribution platform that provides a variety of benefits for wireless service operators, software developers and computing device consumers. At least one such currently available end-to-end software distribution platform includes logic distributed over a server-client architecture, where the server performs, for example, billing, security, and application distribution functionality, and the client performs, for example, application execution, security and user interface functionality.
The foregoing description of the related art is merely intended to provide an overview of wireless devices and some of the known uses of APIs and as an introduction to the BREW® platform, which can be used in various embodiments of the invention. However, the invention is not to be construed as being limited to a specific physical configuration, implementation, operating platform or environment.
By initiating a communication operation at the target handset optimistically, there is a reduction in delay without any major increase in power consumption. Optimistically refers to carrying out an operation, based on a belief or understanding (based on data, past observations, empirical evidence etc.) that there is a good chance or expectation outcome that the operation will be carried out successfully.